Known from the manufacture of circuit boards are various methods for populating the circuit boards. For example, so-called SMD components (Surface Mounted Device) are mounted on contact surfaces on the front side of the circuit board. THT (Through Hole Technology) components, in contrast, possess connection wires, which pass through an opening in the circuit board and are secured on the oppositely lying side of the circuit board. A mixed populating with SMD and THT components is also possible. The soldering of SMD components occurs, as a rule, in a reflow process. For preparing for this, the circuit board is provided with solder paste at the locations to be populated. This forms solder paste depositions. Then, components are positioned on corresponding solder depositions. The so populated circuit board is exposed to a heat source, for example, placed on a heating plate or fed to a soldering oven, wherein the solder paste melts, whereby a connection of the component with the circuit board is produced.
It can occur that components are defective or stop working in the course of operation. Especially in the case of high cost components or in the case of assemblies with a plurality of components, the complete assembly is not disposed of, but, instead, the one or more defective components are replaced. When a component is removed, as a rule, solder remains, which, however, is not sufficient as solder paste deposition for the securement of the substitute component. Therefore, a subsequent applying of an individually to be determined solder amount onto the circuit board, respectively the carrier or the component, is required. Since the surfaces, respectively the contact locations, on which the solder paste is to be applied, are often very small, an applying of the solder paste according to one of the conventional methods, such as, for example, stencil printing, respectively solder paste printing, is no longer possible. Since the openings in the stencil required for these methods are clearly too small, no solder paste, respectively insufficient solder paste, can be released from the openings of the stencil and, thus, transferred onto the pad, respectively the contact location. Thus, it is not possible to print contact locations, which have, for example, a dimension of 470 μm to 160 μm, with a conventional solder paste of class type 3 or type 4, since the ball sizes of the solder paste of these classes are too large.
An alternative method for stencil printing, respectively solder paste printing, is that where the dispensing technology is by means, for example, of a syringe, respectively cartridge, wherein this method likewise reaches its limits as regards the ball sizes. Typically, the diameters of the solder paste dots dispensed with this method lie at about 300 to 500 μm.
Furthermore, it is known to print solder paste dots by means of jet printing contactlessly on the contact locations. In such case, solder paste deposits with a minimum diameter of about 300 μm can be produced. Smaller diameters are likewise difficult to implement with this technology.
Likewise known from the state of the art is to dunk components, respectively their contact locations, which are to be mounted on a circuit board, in a tub of appropriate depth filled with flux and/or solder paste, in order so to wet the contact locations with flux and/or solder paste. After the pull out of the component from the tub, the contact locations, thus, have flux and/or solder paste for the soldering process. This method works, however, only in the case of components, which have projecting, respectively protruding, contact locations, for example, in the form of balls, pins, etc.